1. Technical Field
The present disclosure relates to a flight control system for an unmanned aerial vehicle, and particularly to a useful technology for achieving redundancy in the flight control function of the flight control system.
2. Related Art
In an unmanned aerial vehicle which flies without a pilot, a flight control unit mounted in an airframe typically performs flight control based on a sensor output signal from an airframe sensor and/or a control signal from a ground facility. In order to improve the reliability of flight control in this kind of unmanned aerial vehicle, a plurality of flight control units may be mounted in the airframe so as to achieve redundancy in flight control function. However, mounting a plurality of flight control units is definitely not preferable in consideration of weight and mounting space, and may be difficult in the first place due to various restrictions.
Thus, according to the technology described in Japanese Unexamined Patent Application Publication (JP-A) No. 8-80898, a flight control unit (automatic control unit) is not mounted in the unmanned aerial vehicle itself, but a plurality of flight control units are provided in the ground facility. With this technology, it is possible to achieve redundancy in flight control function by the flight control units provided in the ground facility while performing flight control of the unmanned aerial vehicle by transmitting airframe control signals to the unmanned aerial vehicle, the airframe control signals being generated by the flight control units of the ground facility based on sensor output signals from an airframe sensor.
However, the technology described in JP-A No. 8-80898 mentioned above adopts a control configuration in which sensor output signals and airframe control signals are constantly transmitted and received via a data link between the airframe and the ground facility, and thus compared with the case where a flight control unit is mounted in the airframe, control accuracy may be reduced. Because the data link between the airframe and the ground facility may have limited data amount and/or data delay, adopting such a control configuration all the time is not preferable when more highly accurate flight control is desired except where such a control configuration is adopted only in an emergency when the main flight control unit has a failure.